1. Field of the Invention
The present invention relates to an inflator used in an air bag system.
2. Description of Related Art
Some inflators used in air bag systems for protecting passengers during a collision use only pressurized gas as an inflation gas source of an air bag. In this type of inflator, it is preferable, in terms of workability when attaching the air bag to a gas outlet of the inflator, that the respective positions of the gas outlet and igniter be removed from each other so that a lead wire extending from the igniter does not cause an obstruction.
U.S. Pat. No. 6,554,315 (see FIG. 2 in particular) discloses an inflator in which the respective positions of the gas outlet and igniter are removed apart from each other. Gas for inflating the bag is sealed inside a reservoir 18, and the gas outlet from the reservoir 18 is blocked by a rupturable plate 74. A rod 76 is disposed in a position facing the rupturable plate 74. A propellant charge 64 is burned when a squib 58 is activated, causing an increase in pressure which ruptures a rupturable plate 40. Simultaneously, the rod 76 is pushed, thereby rupturing the rupturable plate 74. Thus the gas in the reservoir 18 is discharged to the outside through a discharging hole 92. The bag is connected to a gas generator via a manifold 8.
In the inflator of U.S. Pat. No. 6,554,315, the igniter and gas discharge hole are positioned at opposite ends of the axial direction of a housing, and therefore a lead wire extending from the igniter does not cause an obstruction when attaching the air bag. As a result, attachment can be performed easily.
In the inflator of U.S. Pat. No. 6,554,315, a mechanism which warms the pressurized gas is activated by ignition of the propellant charge 64, and hence the gas that is discharged into the bag is likely to be cooled by adiabatic expansion. As a result, it is difficult to secure sufficient pressure in the bag and a sufficiently long inflation period. These are points which require improvement.